This invention relates to consumer appliances and, more particularly, to an electronically-based controller for such appliances.
In the past, consumer appliances such as dishwashers, clothes washers, or the like, wherein a user selects an operating cycle of the appliance, have utilized an electromechanical sequencer for control purposes. Typically, such a sequencer includes a motor driven rotating drum having a plurality of cam tracks thereon. Cam followers riding on the cam tracks operate switches which control the application of power to the various electromechanical components of the appliance. While generally effective, such a sequencer suffers from a number of disadvantages. For example, the range of these sequencers is limited by the drum rotation speed and the number of positions required in the cams. An additional limitation is in the lack of flexibility in cycle selection which results in limited available options and only minor cycle to cycle differences. Further, the ability to perform diagnostic routines is severely limited when using an electromechanical sequencer.
In order to overcome the foregoing disadvantages of an electromechanical sequencer, it has been proposed to utilize an electronic controller. Some of the proposed electronic controllers utilize a microprocessor or microcomputer as the main sequence controller. In any event, these electronic controllers use individual outputs with relays to drive the electromechanical components of the appliance. Such a design has the disadvantage that it requires a substantial number of electronic outputs and associated drive circuitry.
It is therefore an object of this invention to provide an appliance controller having the versatility of an electronic controller but still retaining the output simplicity inherent with an electromechanical sequencer.
It is another object of this invention to provide such a controller having the capability of checking for the proper operation of the electromechanical sequencer.